SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7db9f69452e67256c5f953cb82a278482d85681216e1705f8016ef04b48bbeb3' 
  AND token = 'QjLg6W8iZmOJfszz5tXBgk/0APNenHXqg+KWAIuPnUM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}